Idle is self adjusting on me.... wait, wtf?

ok, so i followed the service manual exactly to adjust the idle.

I plugged that hose going to the idle control valve and the connector on the throttle body.

then adjusted the idle to 750 rpm approx.

well, that was a week ago.

and guess what? it's back down to about 600 rpm and sometimes when i come to a stop, especially a quick stop, it drops shaking the whole car, to about 300 rpm.

And i also got the oil light blinking at me. Well, i looked that up in my handy dandy owners manual, and it says that there's barely enough oil to lubricate the motor. So i go and check the oil, it comes up as FULL and it looks like new ( i only have 200 miles on the oil change and just did a full seafoam dealio)

so i restart my car, and the light is gone. No problems with that since.

however, when the idle drops WAY down like that, the light obviousely comes on because the engine is not turning fast enough to keep up the oil pressure.

NOW, what could be causing this? i just readjusted it and it's working fine like it was when i adjusted it the last time.

This has me stumped, and i usually don't get stumped on my honda when it comes to idle problems because my car's pretty much had it all.

Any ideas?

oh, and i'm using castrol GTX 10w-30 oil with a bosch filter.

First thought: look for a vacuum leak.

I did that, i ran carb cleaner over ALL of the vacuum hoses and gaskets under the hood that i could see.

the only thing that came of it, was the intake manifold gasket made some bubbles when i sprayed that.

Hmmm, that's not good... it could in fact be a vacuum leak due to a crumbling gasket. I had that happen on my first '87.

But would that really lower my idle? I mean, once i've got it tuned where it's at, wouldn't it have allocated for the slight leak out of the intake manifold?

Not really, no... especially since if your gasket is starting to crumble, it'll likely keep on crumbling: every time you adjust it to match the extra airflow, more will break away and lean it out again. Remember too that the amount of fuel injected is based partially on the amount of air coming into the throttle body, as measured by the mass airflow sensor. A leaky manifold gasket will let in additional air AFTER the sensor and the ECU won't be able to compensate for that.

hmmm. that's gonna be a bitch to replace....

but i don't think it's bringing air IN, i believe it's going OUT. Reason being, is because it doesn't effect the idle when i spray the carb cleaner on the intake manifold gasket.

that would tell me that it's probably running a little rich if it's letting air OUT.

BUMP

i'm still having the problem, idle just went down to 600 rpm from 800.

ok, someone's got to have an idea as to my problem, any help?

No way, that would mean you have serious blow by if it was letting air out...

You intake manifold is always under vacuum at idle. So air wants to get sucked in from any crack or hole it can find.

what about your coolant level and other cooling system components?

also PCV valve.

If you're getting bubbles, you've got a leak of SOME kind, and your description of the problme REALLY sounds like a vacuum leak,

When my previous car had the crumbling manifold gasket, I patched up the missing bit of gasket by just gooping a lot of hi-temp RTV (the hardening type) over the area (while cold, of course, and left it overnight to set up). Try that, or even try a little engine oil instead of carb cleaner - it's thicker and should do a better job of momentarily sealing the leak, so you can tell if it makes a difference.

Quote:

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Originally Posted by A20A1

No way, that would mean you have serious blow by if it was letting air out...

You intake manifold is always under vacuum at idle. So air wants to get sucked in from any crack or hole it can find.

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What? you don't believe me?
And if I do have serious blow by, wouldnt' that have something to do with the valve adjustment? I just recently did it for the first time, and it quieted down a bit, but when it starts cold, it makes quite a bit of noise.

The idle is going down faster now that i can keep up with it. I have to adjust it every day.... in fact I adjusted it this morning to 1000 rpm and now it's down to as low as 500 rpm. The oil pressure warning light comes on, I start losing power to my stereo etc. so if it's the intake mani gasket, it's getting worse.

Quote:

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Originally Posted by A20A1

what about your coolant level and other cooling system components?

also PCV valve.

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Coolant level slowly goes down due to a small leak. I also noticed that under the carpet on the passenger side it is SOAKED. I don't know in what, but i was installing my car stereo when i noticed it.

PCV valve was replaced about 3k miles ago.

Radiator cap hold pressure, the cooling system holds decent pressure, but after about a minute, it starts to lose pressure.

The only other known problem that the car has, is that the thermostat get's up really high at idle..... like 1mm from the red zone. I've never kept it turned on to the point of overheating. It also leaks about a 1/2 quart of oil between oil changes.... that is the oil pan gasket. My gas mileage just went down to 25 mpg from 27 also.... but that was right after i got my new exhaust installed, so i figured that was it, seeing as it's the AeroTurbine and it severely reduces back pressure.

Quote:

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Originally Posted by Soundy

If you're getting bubbles, you've got a leak of SOME kind, and your description of the problme REALLY sounds like a vacuum leak,

When my previous car had the crumbling manifold gasket, I patched up the missing bit of gasket by just gooping a lot of hi-temp RTV (the hardening type) over the area (while cold, of course, and left it overnight to set up). Try that, or even try a little engine oil instead of carb cleaner - it's thicker and should do a better job of momentarily sealing the leak, so you can tell if it makes a difference.

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Looks like i'll try and replace those gaskets, do I have to take the whole intake mani off to replace the gasket? Actually, i'll probably do it anyway just because I can then clean everything behind the motor.

I wasn't trying to seal the leak using carb cleaner. I use it to find vacuum leaks across the hoses. And if the engine buckles, then there's a leak.

The engine did not buckle when i sprayed the carb cleaner on the intake mani gasket, so i assumed it was fine for the time being.

Ok, got the intake mani gasket ordered, i'm going to pick it up tommorro around noonish.

Hope all goes well and let me know if you guys have any other ideas.